Achieving high strength and high electrical conductivity in Cu-Cr-Zr alloy by modifying shear banding during rolling

An economical and practical thermomechanical process that is able to achieve a good combination of strength and conductivity is highly desired for the copper alloys. Here, a new multi-stage thermo-mechanical treatment, characterized by a pre-rolling with small strain followed by a short-time aging before the secondary rolling and aging, is implemented in the Cu-Cr-Zr alloys. Its effect on the mechanical and electrical properties of the alloy is investigated, as well as the mechanism for improving the properties. Strength and ductility are improved at the expense of only a little electrical conductivity compared to those alloys that have undergone conventional single-stage thermomechanical treatment. The pre-rolling and pre-aging result in dense, dispersive and stable shear bands, which contain lots of dislocations and fine grains. Dislocation strengthening is the main reason for the increased yield strength, while heterostructure consisting of microstructures inside and outside the shear bands gives the processed alloys good tensile plasticity. Our studies shed some lights on development of a short and cost saving thermomechanical process for the Cu-Cr-Zr alloys. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

An economical and practical thermo-mechanical treatment process is desired for achieving a good combination of strength and conductivity in copper alloys. In this study, a new multi-stage treatment method involving pre-rolling with small strain and short-time aging before secondary rolling and aging is implemented in Cu-Cr-Zr alloys. The results show that the strength and ductility are improved with only a slight decrease in electrical conductivity compared to conventional single-stage treatment. The pre-rolling and pre-aging processes lead to the formation of dense, dispersive, and stable shear bands with high dislocation density and fine grains. Dislocation strengthening contributes to increased yield strength, while the heterostructure comprised of microstructures inside and outside the shear bands provides good tensile plasticity. This study sheds light on the development of a simplified and cost-saving thermo-mechanical treatment process for Cu-Cr-Zr alloys.